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原文传递 Influence of Grain Size on Sediment Transport during Initial Stages of Horizontal Dam Break–Type Flows

题名：	Influence of Grain Size on Sediment Transport during Initial Stages of Horizontal Dam Break–Type Flows
正文语种：	英文
作者：	Ilya K. Othman, Ph.D.1; Zhonglian Jiang, Ph.D.2; Tom E. Baldock, Ph.D.3
作者单位：	1Senior Lecturer, School of Civil Engineering, Univ. Teknologi Malaysia, 81300, Skudai, Johor, Malaysia; Research Fellow, Center for Coastal and Ocean Engineering (COEI), Univ. Teknologi Malaysia, Kuala Lumpur 54100, Malaysia (corresponding author). 2Lecturer, National Engineering Research Center for Water Transport Safety, Wuhan Univ. of Technology, Wuhan 430063, China. 3Professor, School of Civil Engineering, Univ. of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
关键词：	Dam-break flow; Grain size; Sediment transport; Sheet flow; Unsteady flow
摘要：	The influence of grain size on sediment transport during the initial stages of dam break–type flows over horizontal mobile sediment beds was investigated through dimensional analysis and experiments. A new dimensional analysis reconciles the unbalanced dimensions in Bagnold’s formulations describing the grain size influence on steady-flow sediment transport and indicates that the sediment transport is inversely proportional to the square root of the grain size, consistent with Bagnold’s empirical correlation. Total transport rates were measured for quartz grains ranging from 0.22 to 2.65 mm in diameter. Regression between the dimensionless variables indicated that the mobility number collapses the sediment transport data better than the Shields number and indicated that the total sediment transport is approximately inversely proportional to the square root of the grain size and the velocity to the fourth power. The Meyer-Peter Müller transport model based on the Shields number requires transport coefficients for the finest sand that are significantly larger than the conventional values suggested in the literature, between 30 for ks = 2.5D50 and 40 for ks = D50. The values for other sediment sizes are closer to conventional values, within the usual range of 10–12 for ks = 2.5D50, but somewhat higher at 16–22 for ks = D50. The occurrence of sheet flow in a suspension regime appears possible, which may explain the significantly larger transport coefficients required for the finest grain size.
出版年：	2019
期刊名称：	Journal of Waterway, Port, Coastal, and Ocean Engineering
卷：	145
期：	3
页码：	1-12